JPS6158206A - Method of producing thick film positive temperature coefficient semiconductor element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a thick-film positive temperature coefficient semiconductor element that does not require glass frit, among planar heating elements used for heat insulation and heating of equipment, etc. It is.

Conventional structure and its problems Elements consisting of BaTiO3 half-core elements have switching characteristics in which the resistance value rapidly increases above a predetermined temperature and self-heating characteristics after switching, and the temperature rise characteristics are rapid and the self-temperature decreases. It is widely used because it has a control function and does not require an external control circuit.

Conventional positive temperature coefficient thermistor heating element 1d was obtained by pressure molding BaTiO3 semiconductor powder and then firing it, but it was considered difficult to obtain a practical thick film positive temperature coefficient thermistor heating element. .

Conventionally, the following methods are known for processing BaTiO3-based semiconductors into a film.

■ After forming into a disk shape, the fired product is polished into thin pieces.

■ Form a thin film on the substrate by vacuum evaporation.

(2) Add conductive additives and 7 liters of glass to B2LT process 05-based semiconductor powder to form a paste, screen print on a substrate, and then bake.

However, in the method (2) above, since the crystal grain size of the 82LTio 5-based semiconductor is large and brittle, it is extremely difficult to polish it into a film. Furthermore, the method (2) is cumbersome to operate, and it is difficult to obtain a large amount of power suitable for the heating element. Furthermore, in method (2), the sheet resistance tends to be high and control is difficult, and it is not suitable for heating elements, and the glass 7 lift must be prepared and fired in advance.
It is troublesome and depending on the material of the glass frit, ga
This degrades the switching characteristics and self-heating characteristics of the Ti03-based semiconductor. Then, by adding glass 7-line, it is susceptible to thermal shock due to the difference in heat resistance and M expansion coefficient between BaTiO3-based semiconductor and glass frit, and heat conduction is hindered. Furthermore, it is difficult to uniformly mix conductive additives and glass frit, which is one of the causes of variations in properties.

Purpose of the Invention Therefore, the present invention solves the manufacturing complexity that was a drawback of the prior art, and by forming a thick film without using glass frit, it has excellent thermal shock resistance and thermal conductivity, and has uniform properties. It is an object of the present invention to provide a method for easily manufacturing a thick film type positive characteristic semiconductor device having the following characteristics.

Structure of the Invention The method for manufacturing a thick film type positive temperature semiconductor device of the present invention includes
An attempt was made to obtain a thick-film type positive characteristic semiconductor element by applying a paste-like mixture of i0B optical semiconductor powder and adding 1 to 60% by weight of NdB to form a thick film on a substrate, and then firing it. It is something to do.

In the conventional method of using a conductive additive and glass frit, a conductive additive is required for electrical connection between BaTiO3-based semiconductor powders, and a glass frit is required to physically connect BaTiO3-based powders together. Met.

However, the present invention is characterized in that NdB6 is used as a material that functions as both a conductive additive and a glass frit. This NdB6 is a conductor at room temperature, and when the temperature reaches 1000-1100°C or higher, a portion of it decomposes and B2O3 is precipitated on the particle surface, but the inside of the particle remains intact and decomposition is prevented by the B2O5 film on the surface. Ru. Therefore, B&TiO5 based semiconductor powder and NdB6
When the powders are mixed and fired, the B2O3 precipitated on the surface of NdB 6 plays the same role as a glass frit, and the inside of the particles acts as a conductive additive, so just adding NdB 6 eliminates the need for a glass frit. A thick-film type positive characteristic semiconductor device with no oxidation can be obtained.

Furthermore, by adding a conductive metal, the thermal conductivity becomes better than that of glass 7 liters, which has poor thermal conductivity, and the thermal shock resistance also improves.

DESCRIPTION OF EMBODIMENTS Below, embodiments of the present invention will be specifically explained with reference to FIG.

Example 1 Adding 1.0 mol% Nb 20 S to BaTiO3
After firing at 300°C, it is pulverized to obtain a B&TiO3 semiconductor powder. A paste-like mixture 1 is prepared by adding 15% of the total weight of NdB6 powder to the BaTiO3-based semiconductor powder and mixing uniformly, and then adding α-terpineol.

On the other hand, a pair of electrodes 3.4 made of a conductive material such as λg is provided in advance on the substrate 2 made of a film 1205, etc., and a part of the electrodes 3.4 remains on the electrodes 3, 4. The paste-like mixture 1 was applied by screen printing, etc., and heated at a heating rate of 10'C/win from room temperature.
The temperature was raised to 350°C, held for 1 hour, and then allowed to cool in the furnace. In this way, a thick film type positive characteristic semiconductor device was obtained.

Example 2 In the same manner as in Example 1, 3.0 molti L was applied to 3aTi05.
After adding a2O3 and firing at 1250°C, crush it to obtain B
Obtain aTi0s-based semiconductor powder. NdB 6 powder in an amount of 35% by weight based on the total weight is added to the BaTiO 3 -based semiconductor powder and mixed uniformly, and α-terpine γ-al is further added to form a paste-like mixture 1. Next, as in Example 1, the electrodes 3 and 4 were provided on the substrate 2 in advance, and the paste mixture 1 was applied by screen printing or the like so that a portion of the electrodes 3 and 4 remained, and the mixture was left at room temperature. The temperature is raised from 10 to 1000°C at a heating rate of 10'C/m/m, held for 30 minutes, and then allowed to cool in the furnace. In this way, a thick film semiconductor device was obtained.

The sheet resistance at room temperature of the thick film semiconductor device thus obtained was 3.3 KQ/ci in Example 1, and 1 and 4 Ω/Ca in Example 2, and the respective temperature and resistance values were The relationship was as shown in Figure 2. In FIG. 2, "B" shows the characteristics of the device obtained in Example 1, and "B" shows the characteristics obtained in Example 2.

Effects of the Invention As described above, according to the manufacturing method of the present invention, the NdB6 powder functions as both a conventional conductive additive and a glass frit, and has sufficient effects on electrical and physical connections. ,
A thick film type positive characteristic semiconductor device can be obtained without the need for a glass cut.

Furthermore, by using NdB6, a conductive metal with good heat conduction, instead of 7W glass, which has poor heat conduction, the heat conduction is improved and the thermal shock resistance is improved. moreover,
Since it can be manufactured by screen printing, etc., it is easy to work with and mass production is possible.

In the present invention, any BaTiO3-based semiconductor powder may be used as long as it is made into a semiconductor by adding various additives to BaTiO3. In addition, the addition amount of NdB6 powder was specified as 1 to 60% by weight based on the total weight because if it was less than 1% by weight, the area resistance would be too high and it would be unsuitable for a heating element. On the other hand, if it exceeds 60% by weight, the sheet resistance becomes too small and the self-control characteristics (PTC characteristics) become small, making it unsuitable for use as a heating element. Furthermore, although an organic solvent (α-terpineol in the example) was used to make the BaTiO3-based semiconductor powder and NdB6 powder into a paste, any solvent may be used as long as it can be made into a paste.

As described above, according to the present invention, it is possible to easily manufacture a thick film type positive characteristic semiconductor device that does not require a glass frit.
Its practical effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing a thick film type positive characteristic semiconductor device obtained by the method of the present invention, and FIG. 2 is a diagram showing the relationship between temperature and resistance value of the device according to an embodiment of the present invention. 1... Paste mixture, 2... Substrate, 3.4... Electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] A thick film type positive characteristic semiconductor element characterized in that it is made by adding 1 to 60% by weight of NdB_6 to BaTiO_3 based semiconductor powder and making a paste mixture, which is coated on a substrate to form a thick film, and then fired. Production method.